1. Field of the Invention
This invention relates to a fuel injection rate control system for an internal combustion engine, such as a diesel engine.
2. Description of the Prior Art
Diesel engines are supplied with fuel by means of fuel injection pumps, which pressurize fuel periodically with respect to rotation of engine crankshaft to effect fuel injection into the engine combustion chambers. In general, the fuel injection pumps have adjustable fuel metering devices to control the rate of fuel injection which determines the power output of the engines.
U.S. Pat. No. 3,630,643 to Eheim et al. discloses a fuel injection pump equipped with an electrically controlled fuel metering device. This metering device includes a mechanical member or collar, an electrically-powered actuator, and a signal generator. The position of the collar determines the rate of fuel injection. The actuator serves to adjust the position of the collar. The generator outputs a signal representing the position of the collar. Signals indicating the power output required of the engine and the speed of the engine are fed to the metering device, which determines a desired position of the collar, that is, a desired rate of fuel injection, on the basis of these signals. Also, the signal indicative of the collar position is fed to the metering device. On the basis of the desired collar position and the actual collar position derived from the collar position signal, the metering device generates a control signal to adjust the actuator. The control signal is designed such that the actual collar position will match or track the desired collar position. In this way, the metering device uses a feed-back or closed-loop control in adjusting the position of the collar which determines the rate of fuel injection.